Using Particle Effects and Vertex Animation to Simulate Large Groups of Animated Meshes

Unreal has a script to do it in 3ds max

https://docs.unrealengine.com/en-US/…ool/index.html
Vertex Animation Tool

https://docs.unrealengine.com/en-US/…hes/index.html
Vertex Animation Tool - Timeline Meshes

https://docs.unrealengine.com/en-US/…hes/index.html

Also, check out this youtube talk by my colleaguehttps://youtube.com/watch?v=EUTE1SoOGrk

Niagara has a module to sample a static mesh and get location points on the surface. You can see that module in the Bird Tree Niagara screenshot. If you want specific areas of a mesh you can sample a Material area. So I just selected the areas where I want the birds to land, and placed them in a different material.